How do I remove punctuaution from a string - c++

Question

I am seeking help on a code that reads a string of characters with punctuation included and outputs what was read with the punctuation omitted. I paid a visit to this link C++ Remove punctuation from String I believe my code is solid. When I compile the code it prompts for the string. However upon entering the string and pressing enter, nothing happens there is no output afterwards I've tweaked the code extensively, but to no avail.
int main(){
string line;
cout <<"Please Enter a line"<< endl;
while(getline(cin, line)){
for(decltype(line.size()) index = 0; index != line.size() && !isspace(line[index]); ++index){
if (ispunct(line[index])){
line.erase(index--,1);
line[index] = line.size();
}
}
}
cout<< line << endl;
return 0;
}

Answer 1

You are making this way more complicated (decltype? for this?) than it needs to be. Try:
int main()
{
std::string line;
std::cout <<"Please Enter a line"<< std::endl;
while(std::getline(std::cin, line)){
const char* s = line.c_str();
while(*s){
if (!ispunct(*s)){
std::cout << *s; // not as slow as you would think: buffered output
}
++s;
}
std::cout << std::endl; // flush stdout, that buffering thing
}
}
Simpler is usually better. As a side bonus, this should also be quite a bit faster.

Answer 2

This can be done without any loops. Usage of the algorithm functions is all you need.
In general, if you have a container, and you want to remove items from the container that satisfy a certain condition, you're using a long (and maybe, wrong) approach if you're writing hand-coded loops as you are doing.
Here is an example of usage of the algorithm functions, namely std::remove_if.
#include <algorithm>
#include <cctype>
#include <string>
#include <iostream>
using namespace std;
int main()
{
std::string s = "This is, a, string: with ! punctuation.;";
s.erase(std::remove_if(s.begin(), s.end(), ::ispunct), s.end());
cout << s;
}
Live Example: http://ideone.com/Q6A0vJ

Answer 3

The reason why your code doesn't output anything is because it is stuck in that getline loop.
assuming c++11:
int main(){
string line;
cout <<"Please Enter a line"<< endl;
getline(cin, line);
line.erase(std::remove_if(line.begin(), line.end(),
[](char ch) { return ispunct(ch) ? true : false; }), line.end());
cout << line << endl;
return 0;
}
or
int main(){
string line;
cout <<"Please Enter a line"<< endl;
transform(line.begin(), line.end(), line.begin(),
[](char ch) { return ispunct(ch) ? '\0' : ch; });
cout << line << endl;
return 0;
}